Phospholipase A 2 activity, calmodulin, Ca 2+ and meat quality in young and adult halothane-sensitive and halothane-insensitive British Landrace pigs

Abstract

PSE (pale, soft and exudative) meat is the result of a developmental disorder and is not produced in meat from young (3–11 weeks) halothane-sensitive British Landrace pigs. Formation of the PSE condition is closely associated with the muscle mitochondrial phospholipase A 2 activity, which increases significantly from 12 weeks of age. The increase in phospholipase A 2 activity shows good correlation (r = 0·87) with the increase in post-mortem sarcoplasmic Ca 2+. In halothane-insensitive British Landrace both the phospholipase A 2 activity and sarcoplasmic Ca 2+ level remain constant throughout growth. Significant increases in the levels of endogenous mitochondrial calmodulin, fatty acids and phospholipase A 2 activity, and Ca 2+ (mitochondrial and sarcoplasmic) are observed in the M. longissimus dorsi of adult halothane-sensitive pigs when compared with either young halothane-sensitive or young and adult halothane-insensitive pigs. The enhanced mitochondrial phospholipase A 2 activity is calmodulin-dependent and the increase in activity is postulated to be due to increased endogenous calmodulin.